Have you tried omitting the ResLast field from the select list? Because this should work.

Sure, I actually had the query running without that, but the result set sorts strangely: persons without email addresses have no last names, which is a bit weird. That led me to include last name in the query. I would like to sort on last name without showing it.

Since my fb supports a web-hosted app, I was actually able to do a dodge in the output generator, which is working OK: sort on the extra last-name field, make the last name "hot" if it has associated an email address, but hide the extra field. Hope that makes sense.